The utility model discloses a protective fence lightning arrester live line measuring device of a reactive compensator. The device comprises three segments of cables, an insulating cabinet with a cabinet, and a portable lightning arrester measuring instrument. The insulating cabinet is fixed on a fence. The three segments of cables are respectively fixed on an A phase screw, a B phase screw, and a C phase screw of a lightning arrester insulation base through clips, or are respectively fixed on an A phase conducting bolt, a B phase conducting bolt, and a C phase conducting bolt on the rear part of the discharge counter of the lightning arrester through clips. The device can conveniently, accurately, and smoothly complete 35 kV and 66 kV voltage level lightning arrester test operation of a reactive compensator, realizing total current and resistive current tests specified by preventive test rules. The device makes measuring operation accurate, reliable, and smooth. The device is beneficial for improving working efficiency, and achieving once for all effect.